8.2 and earlier build times
Ben Gamari
ben at smart-cactus.org
Wed May 17 20:15:36 UTC 2017
Herbert Valerio Riedel <hvriedel at gmail.com> writes:
> On Wed, May 17, 2017 at 10:56 AM, Simon Peyton Jones via ghc-devs
> <ghc-devs at haskell.org> wrote:
>> That's great news! Faster than GHC 7.8! We should advertise this :-).
>
> However, not everything is back to 7.8 levels when looking at the
> time-dimension, e.g. for regex-tdfa-1.2.2 (with reasonably similar
> versions of dependencies):
>
Interesting. I tried comparing build times of regex-tdfa-1.1.8 with GHC
8.0.2 and 8.2.1, yet was unable to reproduce this. Rather 8.2 was
significantly faster than 8.0.2 (although not in the profiled build, it
seems),
8.0.2:
real 2m4.403s
user 0m2.233s
sys 4m49.319s
normal build: <<ghc: 91089022760 bytes, 3544 GCs, 254983314/623313256 avg/max bytes residency (29 samples), 1777M in use, 0.000 INIT (0.001 elapsed), 0.277 MUT (49.941 elapsed), 0.972 GC (28.395 elapsed) :ghc>>
profiled build: <<ghc: 53822322480 bytes, 2813 GCs, 152915198/391707624 avg/max bytes residency (24 samples), 1059M in use, 0.000 INIT (0.000 elapsed), 0.177 MUT (29.445 elapsed), 0.527 GC (15.834 elapsed) :ghc>>
8.2.1-rc2:
real 1m37.004s
user 0m1.690s
sys 4m22.921s
normal build: <<ghc: 74407995376 bytes, 2547 GCs, 188938069/574558856 avg/max bytes residency (29 samples), 1524M in use, 0.001 INIT (0.001 elapsed), 66.810 MUT (33.696 elapsed), 79.093 GC (21.746 elapsed) :ghc>>
profiled build: <<ghc: 55111218888 bytes, 2272 GCs, 149652372/540904144 avg/max bytes residency (26 samples), 1336M in use, 0.001 INIT (0.001 elapsed), 51.072 MUT (25.140 elapsed), 58.298 GC (16.143 elapsed) :ghc>>
My methodology was roughly,
$ cabal unpack regex-tdfa-1.1.8
$ cd regex-tdfa-1.1.8
$ use_component ghc 8.0.2
$ cabal configure ; time cabal build --ghc-options='-fforce-recomp -v +RTS -t -RTS' >| 8.0.2 2>&1
$ use_component ghc 8.2.1-rc2
$ cabal configure ; time cabal build --ghc-options='-fforce-recomp -v +RTS -t -RTS' >| 8.2.1 2>&1
The "normal" and "profiled" build metrics are the +RTS -t lines extract
from Cabal's profiled and unprofiled GHC invocations. I believe the
RTS timings for 8.0.2 are broken due to a (fixed) RTS bug, although I
can't come up with a reference at the moment.
Herbert, did these timings come from a VPS?
Cheers,
- Ben
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